


You've Been Thunderstruck

by Zetal (Rodinia)



Series: Sam & Dean Bingo [7]
Category: Supernatural
Genre: Blowjobs, Bottom Dean, Consentacles, Eggs, Healthy Communication, Kissing, M/M, Multi, Obstacles to Communication, Oviposition, Praise Kink, Safewords, Sibling Incest, Tentacles, Trueform Cas, discussions of boundaries, discussions of consent, established sastiel
Language: English
Status: Completed
Published: 2020-07-24
Updated: 2020-07-24
Packaged: 2021-03-05 02:33:24
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,213
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25487038
Author URL: https://archiveofourown.org/users/Rodinia/pseuds/Zetal
Summary: Dean's plans for the evening had involved sex, but in the original plans, it was with some willing random chick or, possibly, if he found a dude that set him off, a dude.  When the thunderstorm cancelled the original plans, the new plans involved porn and his hand.  Never in his wildest dreams would he have thought he would end up with his brother and his brother's boyfriend and his brother's boyfriend's tentacled true form.Best night ever, really.
Relationships: Castiel/Dean Winchester/Sam Winchester
Series: Sam & Dean Bingo [7]
Series URL: https://archiveofourown.org/series/1407799
Comments: 10
Kudos: 53





	You've Been Thunderstruck

**Author's Note:**

  * For [LadyShadowphyre](https://archiveofourown.org/users/LadyShadowphyre/gifts).



> Written for Dean and Sam Bingo  
> Square: Tentacles
> 
> Written for Dean Winchester Bingo  
> Square: Thunderstorm
> 
> Written for Sam and Cas Bingo  
> Square: Established Relationship
> 
> Written for Castiel Bingo  
> Square: Praise Kink
> 
> Special shoutout to LadyShadowphyre whose wonderful enabling made this possible and helped me out so much with this.

It was supposed to be a night of cruising in his baby and cruising for a chick. This stupid thunderstorm had put an end to that. The rain was so hard there was no way there would be anyone at the bars, and all he wanted to do was get home before it got too bad out and he couldn’t see the road anymore. Once he was home, he could stay in the garage, give his baby some special attention all her own since they didn’t get their quality time, and then go steal Sam’s laptop and watch some porn. Sam probably wasn’t using it; he and Castiel loved to take advantage of Dean being gone for Castiel to get into his true form and do unspeakable things to Sam.

What he wasn’t counting on was coming in to see Castiel in his true form with Sam held up in the air in the embrace of tentacles, mouth and ass both full of tentacle while another tentacle teased Sam’s nipple and yet another carded through Sam’s hair. “What the fuck. MY EYES WILL NEVER BE THE SAME!”

Dean felt a little bad as the tentacles withdrew completely from Sam to hide behind wings, and Sam dropped unceremoniously to the ground. “Dean? What the hell are you doing home?” Sam scrambled to his feet, ignoring his current lack of clothes. “I’m so sorry, we thought you were going to be gone all night, we’d never have done this if we though you might be in any danger.” He turned to the wings. “Cas, can you… is there anything you can do…?”

Castiel emerged from behind the wings, stepping toward Dean to stare into his face, head tilted in his perplexed fashion. “Your eyes seem to be fine, Dean. Are you in pain? It seems I was quick enough to avoid permanent damage, but how bad is the temporary damage?”

“Damage? What are you talking about? This isn’t about damage, it’s about me having to see you tentacle-fucking my brother!”

Castiel and Sam exchanged shocked looks. “You… saw my form, correct?” Castiel pushed. “You actually did see something? And your eyes don’t even hurt, you merely saw something you would have preferred not to?”

“Yes, dammit, I saw the tentacles, not understanding what’s so hard about this,” Dean snapped. He had to admit it was fair for them to have expected him to be out all night. Even if he’d struck out with the ladies, he’d still have been gone all night, if it weren’t for the storm. It wasn’t exactly helping his mood.

“Dean… you shouldn’t be able to see that. It should melt your eyes. Did you see his wings?” Sam asked.

“Yes, I saw his… why the hell shouldn’t I be able to see it? You see it just fine!” If this conversation kept up much longer, Dean’s eyes just might start hurting from all the rolling they were doing.

Another long glance between Sam and Castiel, and Dean was starting to understand why some of their friends found it annoying to be around him and Sam. He knew that look. They were having a complete conversation nonverbally that didn’t include him. The exclusion bothered him. Then Castiel’s wings appeared, and Dean made a point of staring directly at them. “Dean, this should be painful, even blinding to you. With Sam, I was willing to take the risk because the romantic bond between us made it possible that it was safe, that he was recognized as my mate despite no formal declarations. I don’t understand why you aren’t affected.”

“Well, there’s a couple possibilities I can think of,” Sam said. “One…”

“Don’t go there, Sammy. Don’t you accuse me of being in love with your boyfriend.”

“I wasn’t going to accuse you of anything, but yeah, that was one of the possibilities,” Sam admitted. “Of course, Cas would have to love you back, but still, perfectly reasonable possibility.”

“And you’re just okay with that?” Dean was learning so much tonight. Why Sam would be okay with that, he couldn’t imagine, but Sam didn’t sound bothered by the possibility at all.

Sam just shrugged. “Monogamy is a human thing, and you may have noticed, but lots of humans aren’t very good at it, and even the ones who are might choose something else. Jess and I were hoping to find the right person or people to open our relationship to, because with just the two of us it didn’t feel quite complete. If you and Cas feel that way about each other, and you’re good with the idea, I have no problem sharing him with you.”

That was not something Dean would ever have expected to hear. He could not deal with that right now, not when the emotions he’d very carefully buried were threatening to burst out of their cage, dragging who knew what else buried in there with them. “Okay. What were the other possibilities you considered, then?”

“The bond’s a soul thing among humans, and you and me are soulmates, according to Heaven’s rules.” Dean shook his head. Not helping. So not better. “Don’t argue with me, you know I’m right on that, which would be a possible reason you could see him.”

Sadly, Dean could not, in fact, argue. He could complain, but it wouldn’t do any good. Heaven’s stupid rules were stupid, but they were the rules. “Okay. Any others?”

“Yeah, this one’s a bit of a stretch but it’s worth considering. You know it’s tentacles because he told you that, you’ve got a thing for tentacle porn, you’re curious what the tentacle fucking is really like and between that and you two being best friends, it’s good enough for you to see things. After all, it’s gotta be really weird, getting fucked by tentacles you can’t even see.”

Now that, that was one Dean could admit to without examining anything too deeply. “Yeah, okay, that one I could see. That it? You done?”

“Yep. Think that covers it. Cas? Any ideas?” Castiel shook his head. “Okay. Cas?”

Castiel disappeared behind his wings, and when they parted, the tentacles were back. Now that they weren’t stuffed into his brother, Dean could get a proper look at them. The colors shifted between purples and blues and greens and black, as the tentacles writhed around… eyes? Okay, that was weird, slightly off-putting, but still, tentacles. Then one extended toward him, the tip hovering mere inches from his hand. Dean looked over to Sam for an explanation.

“He’s inviting you to pet the tentacle. There may be some risk, but I wouldn’t expect any problems. Be gentle at first, but don’t worry too much about hurting him. If you tried you probably could, but it would be hard to do unintentionally.” Dean still hesitated, and Sam read his mind. “It’s not inherently a sex thing, not that one. It’s like touching his arm or something. But Dean, I mean this, I’m not setting any limits on what you and he can do without me considering it cheating. You want to get tentacle fucked, you are totally invited.”

Dean reached out, hesitantly putting a hand on the tentacle in front of him. He’d expected… not this, for sure. Slimy? Even though he could see perfectly well that it wasn’t dripping slime? Scratchy, like a snake’s skin? Tough? Instead, it was smooth, kind of silky, and he wanted so bad to know what it would feel like sliding inside him. It would probably require lubrication, but… no. He was not going to let himself start thinking too hard about that. He glanced over at Sam guiltily.

Sam had a tentacle around his waist and one petting his hair. Now that, Dean got. Petting Sam’s hair was one of the best feelings in the world. Having a tentacle holding him like that? Would that feel good?

He didn’t have time to wonder long, as another tentacle reached for him, wrapping itself firmly around his back. It felt like getting a hug, although the boneless tentacle didn’t quite feel like an arm. If he closed his eyes, it was still obvious that he was being hugged by a tentacle. It felt great.

It was rather embarrassing to admit, given his connoisseur status with regard to tentacle porn, but he was at a loss for what to do next. Usually, the tentacles took charge and did whatever they felt like doing, but there was no way Castiel would do that. For that matter, in the porn, he usually remembered clothes being ripped off. That gave him a direction. He wasn’t particularly attached to this outfit, but on the other hand, why ruin perfectly good clothes when they had such a quick turnover rate anyway? It would give him a chance to check on Sammy, too, make sure he was really okay with this.

Castiel helped with removing the clothing, once he’d figured out what Dean was doing. A quick glance at Sam reminded Dean that his brother was equally naked over there, which really should bother him more than it did. It did raise a question, but not one Dean was brave enough to ask aloud: was this going to be a threeway, with Cas tentacle-fucking them both at the same time, was Sam just going to watch and maybe play a little with a couple tentacles in a non-sexy way, or was Sam going to take off?

“Dean, can you not hear Castiel?” Sam asked.

Apparently not, unless Sam was messing with him. “He saying something?”

“Huh. Weird, since you can see him, you should be able to hear him… anyway, Castiel wants to set up a safeword for you. He knows me and what I like and what’s triggering for me, but you… as far as either of us knows, you have no prior experience with this, just fantasies. So we’ll pick a series of safewords. First one: hard stop. You hate what’s happening and don’t want to go any further with it.”

Dean raised an eyebrow. Good for Cas, but he did not want to think about the implications there, that Sam did have prior experience with this. It was possible he just meant that he and Cas had been doing this a while, but it was equally possible that there was something else that Sam had never talked to Dean about. “Penguin.”

“Penguin? Really?”

“Yeah, it’s kinda mood-breaking because they’re so adorably ridiculous, it’s what I usually use,” Dean explained. He refused to be safeword-shamed by his little brother. “Next?”

“Next one, you need a minute to adjust to something that feels weird, or you want to think about something and decide whether you want to continue. Pause button rather than stop.”

So not something mood-breaking, just something unusual. Eventually, he decided, “Squid. Keeps with the nautical theme but they have tentacles so it’s still in the mood.”

“Fair enough then. And finally, if Castiel thinks he notices something and stops but you’re still good and want him to continue.”

“Seaweed?” He should’ve saved squid for this one, probably. “That it?”

“Yeah. So, uh, awkward question I know, but given the communication issue… is it okay for me to be out here? I know it’s not ideal, but would it ruin the mood?”

Dean shook his head without hesitation. “If you’re willing to be out here, I’d rather you stay anyway. Hardly the first time you’ve been in the room while I get laid. You want to participate, that’s fine, it looks to me like Cas has plenty of tentacles for both of us.”

“Fair enough, then,” Sam said as his worried expression faded into a soft smile. “Any questions for me or Cas?”

“Yeah.” He’d start with the most important one. “In the hentai, there are a lot of times where those girls have no way to talk…”

Sam snorted and bit his lip to hold back the laughter. “Yeah, that’s porn, not reality, bro. It’s no harder to pull back than it is to pull back from having a cock in your mouth. You’ll be able to talk just fine when you need to.”

“Good.” Dean let himself relax a bit at the reminder that reality differed from porn. In reality, he wouldn’t likely have a tentacle the size of his leg shoved in so far it should be up around his heart. Cas wouldn’t hurt him. Maybe some other time Dean might ask him to, but not this time. “Do you have safewords you use with Cas?”

“Yeah, traffic light system. Red for stop, yellow for give me a minute, green for go ahead. I know, it’s not exactly creative, but…”

“Easy to remember and Cas would have no trouble understanding. Anyone who shames you for that deserves a hard red followed by you walking out.” Dean thought for a minute. If he could talk, anything he came up with mid-sex could get asked then, so he decided not to start thinking too hard about what was about to happen. “Any recommendations for things that you really like?”

“Not really… best things for me are when Cas gets me all wrapped up and hauls me up in the air, but you’ve never much cared for being manhandled like that, and making out with a tentacle. Figure you’d give that a try with or without an explicit recommendation.”

“Yeah, manhandling, not my thing, but… I like being restrained,” Dean said. “That something Cas is willing to do?”

Dean jumped at the touch of a tentacle on each of his wrists, and then his arms were hauled up over his head. One of the tentacles dropped to gently stroke Dean’s face, while the other wrapped itself three times binding his wrists together above his head. “Like that?” Sam asked with a grin.

“Like that. Perfect.” He turned his face toward the tentacle stroking it, opening his mouth to invite the tentacle in. It tasted like honey as he licked at it. Sam had been right, this was pretty damn awesome. It was kind of halfway between French kissing and sucking cock, but either way, it felt really damn good. Unbelievably good.

Another tentacle wrapped around him, this one going for his chest. He shivered a little as the tip of the tentacle brushed his nipple, and again tentacles wrapped themselves around each of his legs. Looking over to Sam just provided even more stimulation, as his brother was also making out with a tentacle but otherwise was being left alone. Sam pulled off the tentacle. “Hey. Don’t worry. Right now, Cas is focused on you because this is your time. I’m fine.”

“You wanna get more involved, do it,” Dean said. He tried to ignore the way his cock was reacting to the idea, blame it entirely on the tentacles that were nudging their way up his legs toward his balls. He could feel his knees starting to give way as the tentacles started to play with them, and why fight? Castiel wouldn’t hurt him, and if he was on his knees, well, he had no problem with that. Not in this context.

“Cas says to tell you you’re doing great, that he’s glad you’re enjoying this.” Dean gasped a little, and Sam, the bastard, laughed. “You like getting praised? You like being told you’re a good boy, that you’re being so good for your angel?”

“Shut up,” Dean said without any heat. Hard to muster any at the moment. A new tentacle had come up, wrapping itself loosely around his cock, and Dean was trying to hold still instead of thrusting into the coils.

Sam came over to pet Dean’s hair. “It’s okay, Dean, let go. If there’s something you want to do, do it. Castiel will let you know if he wants you to stop.”

Dean shook his head. He liked what he was experiencing, even with the self-repression. On the other hand, getting on his knees may have been a mistake, if his brother was going to be standing so close while so turned on. Sam’s cock was right in his line of sight, and it was kind of distracting.

Sam’s head snapped toward Castiel. “Are you absolutely sure about that, Cas?” A pause, and then Sam was staring at Dean, eyes wide in shock. “So… uh… Castiel says you want to suck my cock?”

“What?” Dean glared at Castiel. Should’ve known the stupid angel would be able to dig that deep into his repression and be awkward enough to actually say it out loud. Friggin’ angel. What could he say, though? He admitted to it, there’s no way Sam let this continue; he lied, Cas would know and probably call things off anyway. “Does it matter?”

“Green.” Dean shook his head. The hell? “Dean, the safewords aren’t just for Cas. You want to suck my cock, I am giving permission. Go for it.” Smug little bastard winked at him. “Certainly solves the problem of you being worried that with Cas focused on you I’m not getting taken care of, doesn’t it? I know, we’re brothers, it’s wrong, but to be honest? I don’t give a crap. We can let this be a one-time because-we’re-sharing-Cas-at-the-time thing, if that’s what you want to do, or we can talk it out afterwards and figure out what changes between us, but for right now? Let yourself go. Enjoy yourself.”

Dean watched as Sam maneuvered himself into position, still wrestling with whether he was going to go through with this or not. Sam’s hand stroking over his hair made up his mind, and he reached out with his tongue to lick at the cock. It felt right, and Dean let himself relax and just keep going with it. “So good, Dean. Such a good boy, taking care of Sammy like you always have.” Dean didn’t know whether the words came from Sam or he was just transmitting Castiel’s message, but it didn’t matter.

He was so high from the words and from what he was already experiencing that it took some time to register what he was feeling when he felt the tip of a tentacle brushing back and forth over his hole. Slimy wasn’t the right word, but unlike the tentacles elsewhere around him, this one felt slick. It could probably slide in, no problem. Dean pushed back against it, hoping Castiel could read the invitation.

Slowly, inch by inch, the tentacle pushed its way inside. Dean let himself enjoy the bizarre sensation, even letting out a moan around Sam’s cock as he took it deeper into his mouth. “It’s good to see you enjoying yourself like this, Dean. You deserve to be allowed to let go and have fun.” This one, Dean was sure came from Castiel. Sam agreed with the sentiment, probably, but the phrasing was all Cas.

Dean turned his head as Sam started to watch Castiel instead of him, and his eyes widened a little as a tentacle different from the others emerged from the depths of the mass. This one was already dripping with some kind of slime, and Dean looked back to Sam for an explanation. “That’s the sex tentacle. It’s special. Do you want it? Want to feel it inside you?” Dean nodded, but that wasn’t good enough. “Say it, Dean. Tell Castiel what you want.”

“Why? He can read my mind, apparently.”

Sam rolled his eyes. “Because Castiel likes to hear it. This may sound weird, but for him, affirmative consent is a real kink.”

Weird, but something Dean could totally roll with. “Cas, dude, please, I want to feel that thing inside me. Do it.” Any doubts that Dean had that Sam was just messing with him disappeared as the tentacles wrapped around him tightened, and the one in his ass already shivered as it pulled out. The sex tentacle was thicker, harder, and it felt fucking amazing as it slid in and stretched him out even more. Between that in his ass and Sam’s cock back in his mouth, Dean didn’t think he even needed the tentacle spiraled around his cock to get him off.

Of course, once they did get off, then what? He’d have to face up to the fact that he’d sucked off his little brother while getting fucked by his little brother’s boyfriend. Mate. Whatever they called themselves now. They’d both given clear permission and invitation, but still, once he was out of the moment could he deal with that without guilt? If this never ended, he’d never have to know.

Sam pulled out, and Dean couldn’t help the whine of protest as Sam crouched in front of him. “Dean. If you regret this, we’ll understand and do what we can to help you, but Cas won’t. I won’t. You can have as much of this as you want. Me, Cas, both of us, whatever. Okay?”

“Sammy…”

“We’ll talk again when we’re done here, but yes. I am sure. Do not beat yourself up out of guilt. Don’t ruin the moment for yourself by worrying about what happens after, because you get to decide what that is. I’m speaking for both Cas and myself, we are in complete agreement here.” He let that sink in, and just as Dean was starting to accept it, Sam added, “May I kiss you?”

“Yeah, sure, that’s… wait. Seaweed.” Sam’s stupid grin made it even better when he closed the distance between their lips, kissing Dean slow and sweet. Dean wasn’t quite ready for it when Sam pulled back to stand back up and get his cock back to Dean’s mouth. Oh well. If Sam was serious, he’d probably get another chance to do it properly.

Speaking of properly. Dean could feel himself getting close to the edge, so he put as much effort as he could into making sure Sam, at least, came first. He could feel Sam just about to let go when Sam interrupted him. “Yellow!”

“What’s up?”

“Just… you sure you don’t want me to finish myself off? You want me to come in your mouth?”

“God yes. Please.”

“Huh. Okay, then. Didn’t expect that.” Sam shrugged that off and started to resume, but then stopped again. “What about Cas? Before you decide, you should know… if he comes inside you, there will be eggs. They’re not that big, but if any stay inside you, you’ll feel them when they decide to come back out.”

Dean’s eyes dropped from Sam’s face to the necklace he wore, even now. The crystal on it was unusual. When he’d first found it and Castiel make the crack about stepping on his unborn child, he’d assumed the angel was messing with him, but now… “That’s really his egg, isn’t it.”

“Yep. It’s really his egg.”

“Oh god…” So much for making sure Sam came first, as Dean could feel himself slipping over the edge at the thought. Even the surprised laugh from Sam couldn’t ruin the moment. An egg? Eggs inside him? Maybe if he asked really nicely and promised to be good for Cas, he could have one to wear himself?

“Of course you can have one of my eggs.” Dean didn’t catch on immediately, not until Sam started to repeat it, but then it hit him. He’d heard Castiel speaking directly. “Dean? You can hear me now?”

“Yes, Verizon Guy,” Dean cracked. Then he remembered he was talking to Castiel. “Just… let it go, okay? I can hear you.”

“Hmm. I wonder what’s changed.”

“Well, you and Sammy still need to finish, so come back here, dude? And Cas, come inside me. Please.” Sam took the hint, returning his cock to Dean’s mouth. It wasn’t long before Dean’s mouth filled with the warm salty cum, and he swallowed it quickly. Castiel wasn’t far behind, and Dean could feel the eggs inside him. There were no words he knew to describe the feeling when one dribbled out as Castiel pulled the tentacock out.

The tentacles unwrapped from his arms and legs. Sam dropped to his knees to hug Dean, and Castiel’s tentacles wrapped around both of them. “That was so good, Dean. I hope you will join us again; you added a great deal of pleasure to this experience.”

“Ask me again after we’ve had a chance to clean up and come down from the high, but yeah, I would love to.” Dean stroked a nearby tentacle. “Why can I hear you now, when I couldn’t before?”

“I have a theory,” Sam said. “I think it’s because you accepted that this is something you want, that you were given enough to let yourself accept it and now that you’re all in, you get it all. Only other idea I can come up with is that it was to force me to stay long enough for you to get the full experience, but that seems a little farfetched.”

“Agreed,” Castiel said. He pulled his tentacles back, hiding behind his wings to change back into a human form. He stooped and picked up one of the eggs, examining it closely before setting it on the table. “Leave that one to harden. If you find any others as we clean up, let me know so I can consume them to dispose of them.”


End file.
